On a phase diagram, the critical pressure is .
A) the pressure above which a substance is a liquid at all temperatures
B) the pressure at which a liquid changes to a gas
C) the pressure required to melt a solid
D) the pressure required to liquefy a gas at its critical temperature
E) the pressure below which a substance is a solid at all temperatures

Question

Quizplus · Accepted Answer

The critical pressure is the pressure required to liquefy a gas at its critical temperature. At this point, the substance exists in a state where the liquid and gas phases have the same properties, and further increase in pressure will not cause the substance to condense into a separate liquid phase.

On a Phase Diagram, the Critical Pressure Is